1. Field of the Invention
This invention relates to accumulator injectors for a gas and/or liquid fueled diesel engine fuel injection system. Such structures of this type, generally, allow for variable injection timing and duration while providing a multiple fuel capability by changing the fuel distribution/atomization nozzle.
2. Description of the Related Art
It is known in fuel injectors to make use of a pressure actuated, dual fuel-type injector which employs a mechanical spring to provide the proper needle seating force. The nozzle valve of the fuel injector is a pintle type, which typically has sealing difficulties due to exposure to the combustion chamber and the relatively large sealing surface required in the pintle type nozzle valve. Also, it is known in fuel injectors to employ a pressure actuated injector which utilizes a combination of a mechanical spring and fluid pressure for proper needle closing and sealing. However, with this type of pressure actuated injector, the fluid used in the injector is the same fluid that is used for preventing gas flow past the injector needle, which limits the operating pressure range. Therefore, a more advantageous fuel injection system, then, would be presented if the fuel injector pressure could be more independently controlled.
Finally, it is known, in fuel injectors, to employ an electronically controlled fuel injector which uses a direct acting solenoid to lift the needle valve. However, this injector utilizes a mechanical spring and requires a reduction of the fuel pressure to produce a timely closing of the needle. Consequently, further electronic controls of the fuel injector pressure while maintaining a relatively constant fuel injector pressure would be advantageous.
It is apparent from the above that there exists a need in the art for an accumulator injector which allows for variable injection timing and duration, and which at least equal the fuel injection characteristics of the known fuel injectors, but which at the same time is capable of injecting gaseous or liquid fuels over a broad range of fuel pressures. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.